6 research outputs found
The role of zirconium in microalloyed steels
Recently there has been a renewed interest in the addition of zirconium to microalloyed steels. It has been used since the early 1920's, but has never been universally employed, as have niobium, titanium or vanadium. The functions of zirconium in steelmaking are associated with a strong chemical affinity, in decreasing order, for oxygen, nitrogen, sulphur and carbon. Historically, the main use of additions of zirconium to steel was for combination preferentially with sulphur and so avoid the formation of manganese sulphide, known to have a deleterious influence of the impact toughness of wrought and welded steel. Modern steelmaking techniques have also raised the possibility that zirconium additions can reduce the austenite grain size and increase dispersion strengthening, due to precipitation of zirconium carbonitrides, or in high nitrogen vanadium-zirconium steels, vanadium nitride. This review gathers information on the compounds of zirconium identified in steels together with crystallographic data and solubility equations. Also brief accounts of the role of sulphides and particles in general on austenite grain size control and toughness are included
Adenovirus DNA Replication: Protein Priming, Jumping Back and the Role of the DNA Binding Protein DBP
Transcription Factor SP2 Enhanced the Expression of Cd14 in Colitis-Susceptible C3H/HeJBir
Adenovirus DNA Replication
Replication of the adenovirus genome is catalysed by adenovirus DNA polymerase in which the adenovirus preterminal protein acts as a protein primer. DNA polymerase and preterminal protein form a heterodimer which, in the presence of the cellular transcription factors NFI/CTFI and NFIII/Oct-1, binds to the origin of DNA replication. DNA replication is initiated by DNA polymerase mediated transfer of dCMP onto preterminal protein. Further DNA synthesis is catalysed by DNA polymerase in a strand displacement mechanism which also requires adenovirus DNA binding protein. Here, we discuss the role of individual proteins in this process as revealed by biochemical analysis, mutagenesis and molecular modelling.</p